The world is "at war" with COVID-19, the U.N. chief said Monday, calling for a wartime logic to be applied to unequal access to the weapons needed to fight the pandemic.

United Nations Secretary-General Antonio Guterres urged governments to apply wartime logic to stark inequalities in the response to the pandemic, warning the crisis was far from over despite rapidly advancing vaccination rollouts in wealthy parts of the world.

"Unless we act now, we face a situation in which rich countries vaccinate the majority of their people and open their economies, while the virus continues to cause deep suffering by circling and mutating in the poorest countries," he said, addressing the opening of the World Health Organization’s (WHO) annual assembly of member states.

"Further spikes and surges could claim hundreds of thousands of lives, and slow the global economic recovery," he said, adding that "COVID-19 cannot be beaten one country at a time."

"The most vulnerable are suffering most, and I fear this is far from over," Guterres said. "We need the logic and urgency of a wartime economy, to boost the capacity of our weapons."

Deadly outbreaks in India, Brazil and elsewhere have pushed the global death toll past 3.4 million, even as rich countries such as the United States, Britain and Israel have eased restrictions. India has witnessed horrific scenes in recent weeks with severe shortages of oxygen at hospitals and crematoriums overwhelmed, although the number of new daily infections has fallen in big cities. However, experts say the real numbers of deaths and infections in India – fueled by a new coronavirus variant and "superspreader" events such as mass religious festivals – are probably much higher than the official figures.

"We are seeing the bodies along the river Ganges, which don't seem to be recorded as COVID-19 deaths but are very likely to be COVID-19 deaths," Ashoka University biology professor Gautam Menon told Agence France-Presse (AFP). India with over 300,000 recorded virus-related deaths, has administered close to 200 million vaccine shots, but experts say the program needs to be ramped up significantly to bring the virus under control.

Another Asian country that has faced criticism over a slow inoculation rate is Japan, where the first mass vaccination centers opened on Monday. "It's wonderful. I can rest easy now. For a long time, a year and a half, I was feeling rather anxious and tense," Hideo Ishikawa, 73, told reporters after he got the shot.

Japanese authorities are trying to speed up their vaccination drive with just two months until the postponed Tokyo Olympics begin. Just two percent of Japan's 125 million population has been fully vaccinated, compared with around 40 percent in the U.S. and 15 percent in France.

Health workers pay 'ultimate price'

Speaking alongside Guterres, WHO chief Tedros Adhanom Ghebreyesus said he wanted 10% of every country's population vaccinated by September. He also paid tribute to the estimated 115,000 health care workers who have died from COVID-19 since the beginning of the pandemic.

"They have saved countless lives and fought for others who, despite their best efforts, slipped away," he said, describing the medical workers lost to the pandemic as having paid "the ultimate price in the service of others."

He said many medics have felt "frustrated, helpless and unprotected, with a lack of access to personal protective equipment and vaccines."

"The number of doses administered globally so far would have been enough to cover all health workers and older people if they had been distributed equitably," Tedros added.

More than 75% of all COVID-19 vaccines have gone to just 10 countries. The health ministry of Israel, one of the nations with the most successful vaccination rollouts, said Sunday that it had proposed lifting all virus curbs on June 1, although restrictions on travelers coming into the country will remain.

Dogs sniff for COVID-19

In sharp contrast, the rollout remains painfully slow in Brazil, one of the hardest-hit countries in the world. Its far-right president Jair Bolsonaro has been widely condemned for his coronavirus skepticism and pandemic management, with Brazil's death toll topping 450,000. But he has remained defiant, leading a motorbike rally through Rio de Janeiro on Sunday as throngs gathered to cheer him on despite the coronavirus risk.

In Saudi Arabia, authorities have tightened the screws on coronavirus vaccine skeptics, barring them from pilgrimages and overseas travel. Such people will also be blocked from universities, malls and offices.

And humans might have an ally in the fight against the virus: dogs. According to research published Monday, dogs – with their remarkable sense of smell – can be trained to detect more than 90 percent of COVID-19 infections, even when patients are asymptomatic. Authors of the research, which is yet to be peer-reviewed, said they hoped it could eventually replace the need to quarantine travelers.